Didn't want to get too wordy, so there's a State Of Play, some key points (such as SEP and the suits) and I've attached the NASA presentation for those who want to dig deeper into what this article was based on.

Didn't want to get too wordy, so there's a State Of Play, some key points (such as SEP and the suits) and I've attached the NASA presentation for those who want to dig deeper into what this article was based on.

Thanks for the shout-out to Altius! That said, AIUI, the NASA baseline for Option-B is using robot arms derived from the FREND Arms that MDA has developed for DARPA and for Goddard's satellite servicing group (with JPL microspine grippers), though we'd love to find a way to stay involved.

Didn't want to get too wordy, so there's a State Of Play, some key points (such as SEP and the suits) and I've attached the NASA presentation for those who want to dig deeper into what this article was based on.

Thanks for the shout-out to Altius! That said, AIUI, the NASA baseline for Option-B is using robot arms derived from the FREND Arms that MDA has developed for DARPA and for Goddard's satellite servicing group (with JPL microspine grippers), though we'd love to find a way to stay involved.

~Jon

It was always going to be a reference to Altius, not just because "it's you" (we've got MDA friends here too) but because Altius' twitter feed is one of the few I follow, as it's very proactive at showing the development work. In a swamp of nonsense on Twitter, that's a great one to follow.

Is there more info on the SEP modules available? Mass, propellant fraction, thrust, isp?

Agreed, that would be vital information. I'd like to see calculations for using the ARV to do a Deimos/Phobos visit instead. If SEP can't do orbit insertion/departure at Mars it becomes redundant at best and useless at worst, at least for anything beyond shuttling cargo to the edge of Earth's gravity well. I'm far from convinced SEP is needed for a Mars mission at all.

Nice article Chris. It presented more information than I had before and helped me understand some of the nuances. There are pros and cons for executing the ARM and supporters and detractors of the mission. I find myself somewhere in the murky middle. I support the goals of the mission but not the target. Any SLS mission to anywhere is going to be super expensive so I would prefer the missions to be chosen that most directly support the stated end goal, which is a manned mission to Mars. To that end I would prefer this long term mission (18 months) to focus more toward Mars and be redesigned around a visit to Phobos, which is believed to be a captured asteroid. All the same systems and capabilities would be tested, but would bear directly on the end goal, unlike the ARM, and would also provide the opportunity to conduct some Mars-specific science once the vehicle arrives. That said the goals are worthy and the lessons learned will be invaluable. You treated the mission, and its budgetary woes with the respect they both deserve. Thank you for that. I have always been the kind of person that will argue passionately for my preferred solution/mission/objective, even if it is not the stated thinking of the main players. But I also believe that once the final decision is made then my battle is either won or lost and it's time to shut up and get behind the mission. So I will continue to argue for the ARM to be redirected toward Phobos until the final decision is made. Then I will be solidly behind the decision - whatever it is.

Is there more info on the SEP modules available? Mass, propellant fraction, thrust, isp?

Agreed, that would be vital information. I'd like to see calculations for using the ARV to do a Deimos/Phobos visit instead. If SEP can't do orbit insertion/departure at Mars it becomes redundant at best and useless at worst, at least for anything beyond shuttling cargo to the edge of Earth's gravity well. I'm far from convinced SEP is needed for a Mars mission at all.

SEP can do orbital insertion/departure at Mars, of course. And if you bothered to read the ARM proposal, you would know the information on mass fraction, Isp, and power (thrust is not the most useful metric when calculating missions for SEP, though of course it's trivial to derive the thrust given Isp, power, and efficiency).

And we could do a Mars mission with solid rocket motors if we really wanted to. SEP isn't "needed" but it is a way to improve the affordability of such a mission.

« Last Edit: 04/22/2015 01:53 PM by Robotbeat »

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Didn't want to get too wordy, so there's a State Of Play, some key points (such as SEP and the suits) and I've attached the NASA presentation for those who want to dig deeper into what this article was based on.

Thanks for the shout-out to Altius! That said, AIUI, the NASA baseline for Option-B is using robot arms derived from the FREND Arms that MDA has developed for DARPA and for Goddard's satellite servicing group (with JPL microspine grippers), though we'd love to find a way to stay involved.

~Jon

It was always going to be a reference to Altius, not just because "it's you" (we've got MDA friends here too) but because Altius' twitter feed is one of the few I follow, as it's very proactive at showing the development work. In a swamp of nonsense on Twitter, that's a great one to follow.

Thank you! Hopefully we'll have some cool videos up this week of our Prospector demo and an animation our marketing VP put together showing the boulder extraction CONOPS. I'll make sure to link to them on Twitter.

I'd like to see calculations for using the ARV to do a Deimos/Phobos visit instead. If SEP can't do orbit insertion/departure at Mars it becomes redundant at best and useless at worst, at least for anything beyond shuttling cargo to the edge of Earth's gravity well. I'm far from convinced SEP is needed for a Mars mission at all.

SEP can do orbital insertion/departure at Mars, of course. And if you bothered to read the ARM proposal, you would know the information on mass fraction, Isp, and power (thrust is not the most useful metric when calculating missions for SEP, though of course it's trivial to derive the thrust given Isp, power, and efficiency).

The funny thing advocates of electric propulsion leave out is how weak the thrust is while going on about ISP. Where is the data that says how long the setup requires to do the ~1.5 km/sec just to brake into High Mars Orbit? I wouldn't advocate a setup that needs a solid 2 months or more to do a burn like that. Dawn had to fire it's engines for years for a gentle rendezvous with its targets; a crew vulnerable to radiation can't afford that much time.

I agree SEP would be perfect for moving cargo, but a crew can fly to Mars more efficiently with methalox. Disprove me by showing how long SEP needs to do MOI.

You thrust for most of the mission duration. There's nothing wrong with that, and it is the optimal solution if you're using SEP or NEP. The extremely high Isp allows for it. The fact you think that's a problem and not a solution shows you do not understand how to do mission design for SEP.

Yeah, you could shorten the duration of the burn by reducing the Isp, but it'd mean using lots more propellant.

SEP can take longer or shorter than a typical chemical trajectory, it depends on how much payload you want to bring.

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

I'd like to see calculations for using the ARV to do a Deimos/Phobos visit instead. If SEP can't do orbit insertion/departure at Mars it becomes redundant at best and useless at worst, at least for anything beyond shuttling cargo to the edge of Earth's gravity well. I'm far from convinced SEP is needed for a Mars mission at all.

SEP can do orbital insertion/departure at Mars, of course. And if you bothered to read the ARM proposal, you would know the information on mass fraction, Isp, and power (thrust is not the most useful metric when calculating missions for SEP, though of course it's trivial to derive the thrust given Isp, power, and efficiency).

The funny thing advocates of electric propulsion leave out is how weak the thrust is while going on about ISP. Where is the data that says how long the setup requires to do the ~1.5 km/sec just to brake into High Mars Orbit? I wouldn't advocate a setup that needs a solid 2 months or more to do a burn like that. Dawn had to fire it's engines for years for a gentle rendezvous with its targets; a crew vulnerable to radiation can't afford that much time.

I agree SEP would be perfect for moving cargo, but a crew can fly to Mars more efficiently with methalox. Disprove me by showing how long SEP needs to do MOI.

Look at the Boeing "six not so easy pieces" architecture.

260 days to mars, 200 days return (450 days on surface).

For comparison DRM 5.0 was 174 days out, 201 days back (539 days on surface). So the Boeing SEP proposal has about 25% longer transit (overall mission actually shorter).

I think one of the key points of the article is that even with a crewed EM-1-like mission and cargo mission the launch rate of SLS would be about once every 2 years which is half the rate preferred by NASA to maintain workforce proficiency (not to mention political support).

I'd like to see calculations for using the ARV to do a Deimos/Phobos visit instead. If SEP can't do orbit insertion/departure at Mars it becomes redundant at best and useless at worst, at least for anything beyond shuttling cargo to the edge of Earth's gravity well. I'm far from convinced SEP is needed for a Mars mission at all.

SEP can do orbital insertion/departure at Mars, of course. And if you bothered to read the ARM proposal, you would know the information on mass fraction, Isp, and power (thrust is not the most useful metric when calculating missions for SEP, though of course it's trivial to derive the thrust given Isp, power, and efficiency).

The funny thing advocates of electric propulsion leave out is how weak the thrust is while going on about ISP. Where is the data that says how long the setup requires to do the ~1.5 km/sec just to brake into High Mars Orbit? I wouldn't advocate a setup that needs a solid 2 months or more to do a burn like that. Dawn had to fire it's engines for years for a gentle rendezvous with its targets; a crew vulnerable to radiation can't afford that much time.

I agree SEP would be perfect for moving cargo, but a crew can fly to Mars more efficiently with methalox. Disprove me by showing how long SEP needs to do MOI.

Look at the Boeing "six not so easy pieces" architecture.

260 days to mars, 200 days return (450 days on surface).

For comparison DRM 5.0 was 174 days out, 201 days back (539 days on surface). So the Boeing SEP proposal has about 25% longer transit (overall mission actually shorter).

...and the IMLEO is much less.

There is always a trade between time and IMLEO. If you don't want to reduce IMLEO (or only want to reduce it somewhat), you can get faster transits than chemical alone.

Just because someone somewhere chooses to optimize for IMLEO doesn't mean you can't optimize for transit time.

Don't know why I need to mention it again. I said this before clearly, is there some part of what I said that was unclear?

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Another thing I would like to see with a reusable SEP tug is just throwing larger robotic landers at mars. None of this slow spiralling in stuff. It would drop the payload long before reaching Mars and return home in time for the next window.

We should be lining up about ten different missions for this thing, not fighting over one.

A successful ARM mission would boost investors confident in companies like Planetary Resources. Mars flyby is just a stunt.

At this point I prefer to attract the interest of private investors than to attract public attention. The public will just read the news of a Mars flyby on their cellphones on the way to work and forget about it quite fast.

Well the asteroid people should see the stakes clearly now: do they "not like" ARM enough to be satisfied getting cut out of it entirely?

If ARM does go to Mars, hopefully they'll be bringing something interesting back. If there's no sample return component, they should at least have the PR sense to stick an empty pressure vessel on the front as a "hab. module simulator." Extra points for Real Big American Flag painted on it.

In all seriousness, why not both ARM and unmanned Martian shakedown? SLS could use the business.